A prefabricated railing is usually secured to the balcony or other base on which it is mounted by means of support-post assemblies spaced apart by a distance of 1 to 2 meters. It is necessary that the railing be extremely rigidly secured so as to be able to withstand outward forces of from 100 to 300 kilograms without breaking.
It is necessary that such a mounting assembly be adjustable within certain limits so as to allow the mounting post to be perfectly aligned even when the base is irregular or nonhorizontal. This is particularly the case when the mounting assembly is being used on a balcony which is pitched slightly outwardly so as to allow water to run off. It is also necessary that such mounting assemblies allow the railing to be mounted on the extreme outer edge of the balcony so as to allow the users to benefit from the maximum amount of space on the balcony within the railing.
It has been suggested to mount the support posts on the base by means of shims which either may have flat parallel faces or be wedge-shaped. This allows a limited adjustment, but makes it almost impossible to tip the post relative to the base.
Another useful arrangement uses a base having three support points, two of which are constituted by adjustable screws so as to allow the foot of the support post to be tipped in virtually any direction and compensate therefore for virtually any type of irregularity in the base. The difficulty of this arrangement is that the foot of the support post is always spaced slightly from the base. This allows water between the foot and the base and therefore can be considerably disadvantageous in the case of freezing of this water and at the same time corrosion of the foot of the mounting post is unavoidable. Another disadvantage is that any lateral force exerted on the mounting post will be effective over a very limited area on the base so that it is possible for the cement to be rapidly pulverized beneath the mounting points of the foot of the support post.
In another known system a mounting block is provided on the base which has a semispherical upper surface and the mounting post has a foot formed with a downwardly concave complimentary semispherical surface that allows the post to rock all-and-socket fashion on the mounting block. A mounting screw passes vertically up through the centers of the two semispherical surfaces. Such a solution is indeed satisfactory from a purely geometric point of view, but has the considerable disadvantage that the mounting post is unable to withstand lateral forces to any significant extent as the mounting screw alone resists displacement of the two elements relative to each other. Furthermore severe misalignment of the mounting block and the support post creates an ugly and highly undesireable appearance.